ARC on Fiber>ZYXEL router..Help needed

[Morten_Valbjorn (Morten Valbjørn)]

Roon Core Machine

Euphony V4 OS running ROON CORE + HQ Player Embedded on this hardware:
ASUS Rampage Apex VI x299mobo with Intel i9 7940x cpu, 64GB quad channel Corsair cl16 ram

Networking Gear & Setup Details

1Gb fiber Ethernet through ZYXEL VMG8825-T50
router > inside ethernet is on Cat 6a cabels for all devices

Connected Audio Devices

Euphony OS is connected via Cat 6a cabel to ALLO USBridge > usb > GUSTARD X16 DAC

Number of Tracks in Library

Not important

Description of Issue

Can’t get ARC function to play

Log from ROON ARC setup:
{
“connectivity”: {“status”:“NetworkError”,“status_code”:504,“error”:“error: Error: ETIMEDOUT, response code: undefined, body: undefined connected? undefined”},
“external_ip”: {“actual_external_ip”:“89.150.137.242”,“router_external_ip”:null},
“natpmp_autoconfig”: {“status”:“NotFound”},
“upnp_autoconfig”: {“status”:“NotFound”}
}

[Morten_Valbjorn (Morten Valbjørn)]

Okay, done default reset on the ZYXEL router and done a reboot.
When router is up again, i activated UPnP + UPnP NAT-T function…pressed apply, and then 1 more reboot and…
BAAM…Its working flawless as it should,
Just to be clear… just these 2 settings is chanced in router, nothing else
Maybe someone else have this solution in front